Exemplary embodiments herein generally relate to a crankshaft, and more particularly, to a middle web crankshaft having a forged stress relief.
Currently many OEMs use forged crankshafts for engines. One type of crankshaft is a middle web crankshaft that has at least one full crank web located between and connecting two neighboring pins. With this type of crankshaft, there is a pin to pin overlap area and a pin to journal overlap area. The stiffness and strength of the middle web crankshaft is dependent on the amount of overlap that can be achieved for the pin to pin overlap area and the pin to journal overlap area. However, most times the pin to pin overlap area and the pin to journal overlap area are not balanced causing uneven stress concentration in the crankshaft. When the strength of the forged crankshaft is an issue, the material strength of the crankshaft typically needs to be adjusted to achieve the required safety factory. For example, it is known to machine a stress notch or stress relief groove into a crank web of the crankshaft for distributing stresses. However, this stress notch or stress relief groove generally only reduces stress in one isolated area of the crankshaft and the additional machining step increases the manufacturing costs associated with the crankshaft.